1. Field of the Art
The present invention relates to a process for the preparation of water absorptive resins obtained by the polymerization of water soluble ethylenically unsaturated monomers, wherein a solution containing a water soluble ethylenically unsaturated monomer as a main component is fed into a vapor phase and polymerized in the vapor phase.
According to one aspect of the present invention, there is provided a process for the preparation of water absorptive resins obtained by the polymerization of water soluble ethylenically unsaturated monomers, wherein a solution containing a water soluble ethylenically unsaturated monomer as a main component is fed into a vapor phase comprising steam or a mixture of steam with at least one gas substantially inert with respect to the polymerization and polymerized in the vapor phase.
According to another aspect of the present invention, there is provided a process for the preparation of water absorptive resins wherein a solution composed mainly of a water soluble ethylenically unsaturated monomer is supplied to a polymerization vessel accommodating the above mentioned vapor phase and polymerized in the vapor phase, the temperature of the inner wall of said polymerization vessel being adjusted to be higher than that of said vapor phase.
In recent years, water absorptive resins have been used as sanitary goods, diapers and disposable dusters in sanitary fields and as water retentive materials and soil improvers in agricultural fields. Besides, they have found use in various fields and applications inclusive of the solidification of sludge, the prevention of dew condensation and the dehydration of oils.
In particular, the water absorptive resins have been increasingly used for sanitary goods such as sanitary napkins and diapers and for building materials, containerized shipments, marine transportation or the like for the purpose of preventing dew condensation, thus making a good deal of contribution to life in society.